Telephone system



NOV. 1, 1932. R TAYLOR ET AL TELEPHONE SYSTEM Filed Jan. 20, 1930 2 Sheets-Sheet l I c n :2 x

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Reginald Taylor Charles Edmund Beale Nov. 1, 1932. TAYLOR ET AL 1,885,650

TELEPHONE SYSTEM Filed Jan. 20, 1930 '2 Sheets-Sheet 2 45 &

V v F3 a Lag-345E Reginald Taylor Charles Edmund Bill! Patented Nov. 1, 1932 isssrse REGINALD TAYLOR, or LIVERPOOL, Ann CHARLES EDMUND BEALE, or LONDONQENG- LAND, essrouoas TO A emcee-0, ILLINOIS, A

ASSOCIATED TELEPHONE AND TELEGRAPH COMPANY, or coaroimrrouor DELAWARE l 1 TELEPHONE SSESTEM.

1 Application fii aeranimy e0, 1930, SerialNo. izipia'and in Greatjliritain February 12, 1929.

j Thepresent invention relates to telephone systems and is more particularlyconcerned with arrangements for establishingconnections over inter exchangef junction lines. Such junctions are frequently of high resist,-

ance'and provision'has hitherto been made A to? for some means ofjjunction compensationor impulse correct on According toone feature of the invention an automatic numerical; switchis arranged to be operated over an inter-exchange trunk line by impulses transmitted over the conductors of the trunk line inparallel and to re-' peat snbsequent impulses to tion of a succeeding switch. I p

According" to another feature. of the m:-

vention an automatic numerical switch is arranged to beset. by incoming impulses and to repeat si bse'quent impulses overtheou-tgomg speaking conductors, the inconnng. and

outgoing speaking conductors being connect ed together only when'a special signal is received back over the outgoing speaklng conductors.

' According toa further featureof the invention ina telephone system including an impulse repeater-situated at the outgoing end of an inter-exchange trunk line,a relay,

in the repeater is arrangedto be operated either when busy conditions are encountered the called'subscriber replies.

The 1'efer1ing to.tl1e following specification which taken in conjunction with the drawings discloses one method of carrying the invention into effect. It will be understood, however, hat this is given by way of by the switch at .the incoming end or when example only and that various modifications may be made in the circuit details by those skilled infthe art without'departingfrom the spirit ofthein'vention. U

in order to ensure satis L factory operation of thGlmPUlSGIQSPOIldIIIQ apparatus at the incomingexchange. 7 Such ey-er;not always en-' it is an ob ect of the extending inter-ex invention will be better understood by;

accompanying Fig. 1" sh'ows a repeater circuit arranged to 7 repeat impulses received over a loop circuit over the two conductors of an inter-exchange trunk line inparallel.

7 Fig.2 showsan'incoming' selector repeater circuit situ'atedat' the other end of the interexchange trunk line andarranged to respond to the impulses transmitted over the two conductors in'paralleland to repeat corresponding impulses in a loop circuit.

A detailed description of the operation of the apparatus shown in the drawings will now be giyenfj' when the repeater shown in Fig. 1 is seizedo'ver conductors lOand 11 a circuit will be closed for impulse accepting relay A as follows: earth at armature 12 of'relay BR,-lo wer winding of relay'A, con tacts associated with armature 13, conductr 11, calling loop,'conductor 10, contacts as'so-j ciated with armature 1 1', upperwinding' of relay A to batter'y, Rely A operates over the foregoing circuit and at armature 14 closes the .circuitto the upper winding of the guard relay B, and upon the operation of the latter relay 'earth'is'connected byway of armature 15 to the release trunk conductor 16 in order to mark the repeater busy; due to the operation of relay'A earth is extended over armatures 14: and 62 to operate'relay GR which short-circuits its lower winding. to render it slow. to release. At varmature 17 earth is extended viaarmature 18 to operate busycontrol relay BC the function of which relay will be described later, while at armatures 19 and 20 the following junction circuit is completed: battery, low resistance .34, armatures 215 22 and 23, upper winding of relay I, armatures 24;, 1 and- 25, conductor 26; armatures 27 and 28, u per winding of the impulse accepting relay earth, and similarly a branch circuit may be traced from battery ia the lower winding of relay I, armatures 20 and 30, conductor 31,

armature 32, lower winding of relay A2, arm

ajture 33 to earth. Consequently the impulse accepting relay A2 ofthe incoming selector will'be operated over both junction lines in parallel, but it must be mentioned that in this 2, armature 29 to When the dialled impulse series iscompleted',

' matures: 41' and 42,

' particular instance armature 41, varmature springs 4a,

the coils of relay I in the repeater are connected in opposition so that the relay will not operate at this time.

Upon the operation of relay A2, relay B2 will be operated over armature 37 thereby at armature 36 preparing the impulsing circuit to the'vertical magnet V Upon the reception of the first series of impulses relay A: in the repeater will 'respond' 'and at its arrnatu-re 22 cause said impulsesto begrepeat'edztor relay A2 in the incoming selector over the .cir= cuit previously traced, whereupon the following circuit will then be completed to :the yer-'- tical magnet V: earth, armatures 37, 36, 38, 39, windingof'vertical magnet V to battery, and in parallel thereto v-iathe windingofre lay G'to battery. The vertical magnet opera atesandraises the shaft and wipers one'step each time it operates; on the, first vertical step the; ofi-normal springs N are operated thus preparing the circuitto the release mag net Z and also completing the following .initial' v energizing. circuit to the test relay G: earth at armature 40 of I relay B2, e2,operated"off'-normal springs N, winding of relay G. to battery. Accordingly, relay G is operated and thereupon completes 'a locking circuit by way of its operated armature 43 and. the interrupter springs 44;, and at .contact 7 3' com'pletes a circuit for relay ,CB which. operates and pre-- pares a lockingcircuitfor itself? atflarmature. 55. It must be mentioned thatbothrelays, B2 and C remain operatedduring the impulsin due to their slow releasing feature.

relay A2. will be held energized and when relay C releases after a shorttime interval,

rotary magnet R energizes over .thefollowing circuit: earth, armature 4'0 ofrelay B2, a1.-

, armaturei45', winding. of the rotary magnet Rflto battery. The operation ofthe rotary magnet causesthe shaft tobe rotated until the wipers engagewith the firstf'set of bank contacts whereupon. the rotary interrupter springs Hare opened, thus opening the holding circuit. to Tthe test. relay G. Upon the release of. the testrelay. G the circuit is alsoopenedlto the rotary imagnet Rat armature. 45 which also restores; ifthe firstset of bank contactstests busy, wiper tfi-will-encounter earth and the following. circuit willbe completed tothe test relay G:. earth at wiper 4L6, armature 4:7,.contacts associated with armature 48,. interrupter operated off 'norm-al' springs N,-. winding. of test relay G to battery.- Consequently relay G. will again complete the circuit to the rotary magnetBlandfthe' wipers will accordingly be moved'into engagement with the nextset ofbanl: contacts. It will be appreciated during. the alternate operation of the test relayG, the slow relay CB willremain energized due. to the effect of the" copper slug. on its core.- The-.wiperscf the switch will be automatically rotated over the bank contacts until an idle line is encountered whereat, upon the release of thetest the rotary interrupter springs, and the rotary magneti R consequent upon its disconnection at armature 4.5, the following circuit will be completed to the switching relay H: Earth, armature. 34-101 relay B2, .winding of relay'H', contactsaassociated' with. armature 458-, interrupter: springs; 44, operated offenormal springs N, winding of relay G to battery. It-mustbementioned here that due to the limitation of current in the circuit by the comparatively highresistance of the switching relay; H, relayG. does not operate at this time.

Upon the operation .of'frelay; H, earthby way offarmature-47' 'is extended'towiper 46fin order to busy theselected connection, while. the following. loop circuitii s also completed'to the. impulse accepting. relay of the switch ahead earth through. upper winding. of; 'pulse accepting.relay, wiper L9, armatures 50 and .51, windingof relay I2, ,left-handwind' ingof polarized relay D2, armature 52, wiper. 531' to. battery, throughlower winding oflim:- pulse. acceptingrelay Relayl2. operatesoven the foregoingcircuit and-at. its armature 54L maintains thQrSlOW releasingrelay GBI energized'via armature 55. I Upon the reception of subsequentseriesof impulses,.relay A2will again beoperatedover. the parallel. circuit, whereat said impulses will :thenbe repeatedTat armature 51 .over the. loop circuit previously tracedto the switches ahead. When the .desii'edconnection hasbeen established and'the called subscriber, answers, current flow in .the calling loop is reversed by the. last switch in the train and in .conse: quence. the polarized. relay, D2 operates an complete'sthe. following. circuit earth, armature 41.0 of, relay. B2,.armatures 56.: and 57,. windingof relay AD. to battery. Relay. AD. 'thereuponoperates and provides. a lockin circuit for itselfby way ofarmatures 5'8 and 47, and wiper 46' to earth fed back from :the. final .selector, at the back contacts of armatures 27 and 32, relayAD- disconnects relay A2 which thereupon releases anddi sconnectsrelay B2 which in turn releases, and at the front contacts of armatures 27' and 32.the speaking circuit" through the repeater and selectoris completed. 7

Battery and earth connections from the final selector willnow be connected'over' the uncti'on-lines to the repeater, whereupon relay- I operates and'at armature 59 extends earth viaarmature 60- to the winding of relay IA. Relay IA" thereupon operates and at: its light armature 61- closesa locking-circuit for itself and at armatures 21 and 23 com due to the reversed battery from the final selector switch, thereby completing a circuit to relay DA. The operation of relay. DA

' causes the direction ofbattery to be reversed 13,; and efl'ects the connecting through of around the calling loop at armatures 13 and 14' and it will be noticed that during the reversal period a comparatively high resistance 63 is connected across the calling loop by way of armatures 64 and 65, thereby reducing the clicks produced in the receivers of the calling and called subscribers; relay, CR releases after its slow period has elapsed in order to remove theshunting effect of resistance 63 Consequent upon the operation of relays IA and I, relay BC will be held operated from earth, armature 17, armatures 59 and 60, armature 66, winding of relay BC to batter i r I ssuming now that the line of the wanted subscriber tests'busy or that all the lines in the selected level of a succeeding selector test busy, the usual busy flash conditions will be set up by the operation of cam springs at the group selector or the'busy relay at the final selector switch; battery is thereby connected to both trunk conductors as a result relay I2 will release and in turn open the holding circuit to relay GB at armature 54. Relay CB accordingly releases and at armature 67 completes a circuit to relay AD which operates the 111185 as already explained. When battery and earth are again connected to the trunk conductors at the conclusion of the flash period, relay I in the repeater'eircuit will be operated thereby causing relay IA to be operated and performing identical functions to thatalready described for a normal call. Consequently, upon the reception of the next battery flash period, relay I will release and at I armature 59 open the holding circuit to relay BC, whereupon relay BC will release since its original energizing circuit is open at armature 18, 'relay IA being locked operated. Uponthere-operation ofrelayI with the next battery and earth period of the busy signal a circuit may be traced to relay BR as follows; earth, armature 17 of relay B, armatures 59, 60 and 66, winding of relay BRto battery, thereby causing relay BR to operate and operated over armatures 68 and 17. Upon the operation of relay BR busy flash will be extended over conductor 69 and armature 12 to the lower winding of relay A, therebycausingrelayAto operateintermittently to repeat the busy signal to the calling loop, while at the same instant the usual busy hold circuit is also completed at armature 70 via the lower winding of relay B in order to maintain that relay energized during the flash "5 periods,

is then connected over the pulses to operate said 2. In'a telephonesystem, a trunk line'ternumerical switch,

1 It must be mentioned at thispoint thatin case it should be desired to hold the switches at the distant exchange operated during the busy condition, the dotted strap shown should be connected between terminals. 71 and 72. With the latter arrangement it will be readily appreciated that the operation of relay BR" will cause a holding loop to 'be connected across the outgoing junction leads tothe distant exchange.

Assuming now thatall particular level dialled of theselec'tor' shown in Fig. 2 test busy; the wipers of the switch extending earth; to the winding of relay CSwhichac'cordinglyis operated. The operating'windin'g of switch ing relay H is then short-circuitedjat armature 48 in order to render that relay inop-- busy-flash circuit erative, and the following junction lines to the repeater: busy flash and earth'over conductor -73, armature 33, lower winding of relay A2, armature32, conductor 31, a'r'matures 30 and 20, lower and upper windings of relay I in series,

winding of relay A2, armature 28 and low resistance 74: to battery.- Similarly the folflash if the call is through a'manual exchange relay A in the I will release, therebyallowing repeater to restore which inturn effects the; restoration of relay B. The release of relay B opens the holding circuit to relay BR,

whereupon thelatter relay opens the holding. at armature 25' circuit to the distant switches so that all the apparatus taken into use is thus-restored to normal in readiness for the nextcall.

We claim:

' 1. In a telephone system, a trunk line terminating in an automatic numerical switch, means responsive to impulses transmitted over the two conductors-of said trunk line in parallel for operating said'switch to connect with a succeeding switch, and means in said first switch for repeating subsequent imsu'cceeding switch.

minating in an automatic means responsiveto impulses transmitted over the two conductors the outlets of armatures" 24, 1 9 and 25,; conductor 26, armatures 27 and 29,- upper foregoing description that again setup 1n" of said trunklinein w1ll then'finally come to rest in the eleventh l step position, whereat the'cam springs 'S Wlll be operated, thereby parallel fonoperatingsaid switch toconnect with succeeding switch, and Tmeans in: said first switch for? repeating subsequent im= pulses over a loopeircuit to loperate said succeedingzswitchw. I e 3". In a telephone/system, ran interofiic'e trunk line terminating in an automatic numerical switch, means responsive to impulses transmitted 'ove'r'th'e two conductors of said: trunk line in parallel for operatingsaid. switch, means in said switchfor repeating subsequent impulses to: a succeeding switch, and means for completing artalking', circuit through said first switch'responsive'to the encounteringrof a. busy condition by the succeedin'gswitch; v 5 V 4-,: Ina telephone system, a selector repeater arranged to' be operated by impulses'transmitted over-.the'two' line conductors-in par allel,'means in said switch for repeating subsequent impulses to succeeding switches to extend: a connection to a called subscriber, and means for completing a talking circuit throughsaid: switch responsive to the en?- countering-of a'busy eonditionby asucceeding switch in the event such condition exists and tothe answering of thecalled subscriber in the event the connection is completed with-; outfa'i'busy condition being encountered. 5'; Ina telephone system, a trunk line terminatlng' in aselector'repeater, outgoingtalkingi conductors for saidswitch, .means for-operatingcsa-id switch" responsive to im aulsesre'ceivecl over said 1 trunk line, means .3 or- -.repeat1ng subsequent impulses to extend a connection to a called subscriber, and means responsive-tothe encountering of a-busy condition": in theestablishment oisaidconnection for directlyIconnectingsaid trunk lineto saidoutgomg talk ng conductors.

6. .Ina telephone system, a trunk linetermina ting in a, selector repeater, outgoing talk-mg. conductors for said swltch, means for operating said switch responsive to im-: pulses received over said trunk l1ne, meanstor repeating subsequent impulses to extend a -con-nectionto; a called isubscriber, and means responsive to the encountering of a busy condition inrthe establishment of said connection in the'event such condition" exists and to the answering oifi the called subscriber in the event the connection is completed with-- out encountering a busy condition fjor direct- V ly connecting. said-trunk line'to'said outgoing'talki-ng conductors,

peater arranged tobe operated by impulses transmitted over thetwo incoming line con-' ductors parallel, means insaid switch for repeating subsequent impulses overa loop circuit:to succeeding switches toestablish a telephone connection, said: relay prepared: when said switch connects with a succeeding switch and com-- pletedresponsive to the; reversal or disconarelay,

1 715111 a telephone system,'aselect-or re a relay, --a circuit for tinuation of current over said loop circuit, whichever takes .plac'efirst and means re,- sponsive to the operation of said relay for completing a talking circuit through said. switch. Y 7

' 8. Ina telephone system, a selector re peater arranged to be operated by impulses transmitted over the two incoming line conductors in parallel, means in said switch for repeating'subsequentimpulses over a loop circuit to succeeding switches to establish a telephone connection, a relay in said switchoperated over said loopcircuit, means for releasing said relay responsive to the receipt.

of .a busy-signalfrom a succeeding switch,v

and means responsive to therelease of said relay for extending said busy signal over said incoming linegconductors.

9. In a telephone system,;a trunk line, a repeater arranged; to receive impulses over a calling. loop and to repeat said impulses 'over' the two conductors of said trunk line inz parallel to establish a telephone-connection, and means for operating said relaywhen the connection has been completed or when busy condition has been. encountered so that the connection cannot be completed.

10. In a telephone system, a trunk :line, a, repeater arranged to receive impulses .over a calling loop and to repeat said impulses over the two conductors of said trunk line in parallel to establish a telephone connection, a relay, means for operating said relay r'espon-: sive to the answering of the .calledsubscriber or responsive to a busy-condition atf'a succeeding point in theconnection, -and;means controlled by saidrelay for reversing the; battery connectionsto the calling loopor for connecting a'busy-signal, to the calling loop dependent upon whether said'relay 'wasoperated responsive to. the answering: otrthe called subscriber or responsive'to abusy condition. a y

11. In a telephone system, a-tru'nkiline, an impulse repeater arranged to receive impulses over a calling loop and to. repeat said impulses overthe 'two conductors of said-trunk line in parallel to establish a telephone connection, a relay arranged tobe operated either when the-called subscriber answers or when a busy condition is encountered in the establishment of the connection, means controlled by said relay when operated in responseto the answeringo-f the called subscribersfor I reversing the battery connections to the calling loop, and a-' resistance connected across the calling loop during said reversal.

'12. In a-telephone system, a trunk-line, an

impulse repeater arranged to receive impulses over a calling loop and to repeat said impulses over the two conductors of-"said trunk line in parallel to establish a telephone connection, arelay arranged to be operated either whenthe' called subscriber answers or when a busy condition is encountered in the establishment of the connection, and means efiective only when said relay is operatedvin response to a busy condition for disconnecting said trunk line and for transmitting a busy signal to the calling loop.

13. In a telephone system, a two conductor trunk line, a simplex circuit including the two conductors of said trunk line in parallel, means for transmitting digit impulses over said simplex circuit to establish a telephone connection, and means responsive to the completion of said connection for converting said simplex circuit into a'loop circuit including the two conductors of said trunk line in series. 7

14:. In a telephonesys'tem, atwo conductor trunk line, a simplex circuit including the two conductors of said trunk line in parallel,

automatic switching apparatus at the distant end of said trunk line, means for transmiting digit impulses over said simplex circuit to control said automatic switching apparatus in the establishment of a telephone connection, means responsive to the completion of said connection for converting said simplex circuit into a loop circuit including the two conductors of said trunk line in series, and means controlled over said loop circuit for circuit including the two conductors of said trunk line in series, said 100p circuit thereafter serving as a holding circuit for the select-or repeater and succeeding switch and as supervisory circuit between said repeater and said selector repeater. In testimony whereof TAYLOR and CHARLES signed our names at Liverpool, England, this 19th day of December, 1929.

REGINALD TAYLOR.

CHARLES EDMUND BEALE.

we the said REGINALD holding said automatic switching apparatus operated.

15. In a telephone system, a two conductor trunk line, a simplex circuit including the two conductors of said trunk line in parallel, means for transmitting digit impulses over said simplex circuit to establish a telephone connection to a called subscriber, means for converting said simplex circuit into a loop circuit including the two conductors of said trunk line in series when said connection is completed, and supervisory means operated responsive to the reversal of current over said loop circuit when the called subscriber answers.

16. In a telephone system, a two conductor trunk line extending from an outgoing repeater in one exchange to automatic switching apparatus in a sec-0nd exchange, a simplex circuit including the two conductors of said trunk line in parallel, means in said repeater responsive to impulses received over a calling loop for repeating said impulses over said simplex circuit to control said automatic switch apparatus in the establishment of a telephone connection, means responsive to the completion of said connection for converting said simplex circuit into a loop circuit including the two conductors of said trunk line in series, a relay in said repeater operated by reversed current over said loop circuit when the called subscriber answers, and means controlled by said relay for reversing the current flow in the calling loop.

17 In a telephone system, a two conductor trunk line connecting an outgoing repeater and an incoming selector repeater, a simplex EDMUND BEALE have impulses received over a call- I 

